Thermionic tube



April 18, 1933.

C. S. FRANKLIN.

THERMIONIC TUBE Filed 0ct.26, 1929 lNVENTOR names 5. mums ATIORNEPatented Apr. 18, 1933 UNITED STATES CORPORATION or AMERICA, ACORPORATION or DELAWARE 'rnnmuroN c TUBE Application filed October 26,1929, Serial No. 402,689, and in Great Britain November 2, 1928.

This invention relates to thermionic threeelectrode tubes or valves, andhas for its principal object to provide an improved triode capable ofbeing satisfactorily employed for the generation of very highfrequencies.

Thermionic three-electrode valves, as at present in common use, comprisea cathode, usually consisting of a heated filament, a control electrode,usually consisting of a grid or mesh of wire or wires, and an anode,generally in the form of a plate. It is found that limitations to thefrequencies of the oscillations which may be obtained with valves ofthis kind are imposed by the leadsconnecting the control grid system tothe external circuit,

by the current carrying capacities of these leads and of the grid wiresthemselves, and by the inability sufficiently to cool the grid electrode or conduct away the heat produced therein.

According to this invention the control electrode of a thermionic valveis made in the form'of a metal plate, cylinder, cone, or other solidconstruction, as distinct from a wire construction.

In carrying out the inventionfthe active portions of the controlelectrode, i. e., those I portions which mainly influence the electronflow, are formed as ribs or other projections upon a solid electrodesituated on the side of the cathode remote from the anode, the said ribsor the like projecting into the cathodeanode space to any extentnecessary to give a desired degree of control. The projections, whichmay or may not be integral with the main body of the control electrode,should be in good electrical and'thermal contact therewith.

1 The invention is illustrated in the accom- 40 panying schematicdrawing, in which Figure 1 is a sectional elevation and Figure 2 asectional plan of a so-called transverse construction of valve inaccordance with the invention. Figure 3 is a section showing theconstruction of the control electrode incorporated in the valve shown inFigures 1 and 2.

Referring first to Figures 1 and 2, a valve 1 V shaped anode forming oneportion of the comprises a disc-shaped metal anode A opposite which isconcentrically mounted a solid disc-shaped metal control electrode G,

K therefor being brought through. the glass,

which is provided with slots or grooves S in which are arranged filamentportions F as shown. The'electrodes A and G are separated and supportedby glass parts M to which the appropriate electrodes are fixed by 5,15;suitable vacuum seals. The filament. portions may be in series, parallelor series-" parallel, as ,may be desired, the connections as shown inFigure 1.-

v Aswill-be seen, the electrodes are in socalled transverse arrangement,both control electrode and anode being in the-form of. disc-likemembers. The control electrode; G is formed with slots or grooves S inwhich Q5, are arranged the filament portions F, as

clearly shown in cross-sectional Fig. 3.

It will be seen that the present inventionprovides a valve in which boththe anodeand' the control'electro-de maybe of ample current 7Q carryingcapacity, while both these electrodes may be arranged to be cooled byoil or similar mediums. Further, the difficulties hitherto experiencedin making adequate connections to the control electrode are mini- 7i.mized or obviated.

1. A thermionic tube comprising a disc-'- shaped anode, a disc-shapedgrid electrode adjacent and parallel to said anode, the grid Q9electrode being provided with grooves, an electron emitting electrodepositioned within the said grooves and a cylindrical member open at eachend, interposed between and having its ends joinedlto said anode 5.

and grid electrodes.

. 2. A thermionic tube comprising a discshaped anode forming one portionof the tube envelope, a disc-shaped grid electrode positioned oppositeto said disc-shaped 9,9 anode and forming another portion of the tubeenvelope, an electron-emitting element mounted between said grid andanodeelectrodes, and'means interposed'between sald disc-shaped gridandanode electrodes maintaining said electrodes in spaced relation.

3. A. thermionlc tube comprlsing a disctube envelope, a disc-shaped gridelectrode and forming another portion of the tube envelope, a cathodemounted between said grid and anode electrodes, and a glassp0rti0ninterposed between said disc-shaped grid and anode electrodesmaintaining said e1ec--- trodes in spaced relation, both said electrodesand the glass portion being the sole means comprising the tube envelope.CHARLES SAMUEL FRANKLIN.

